Apparatus for conditioning air prior to passage over liquid condensing means



Dec. 3, 1963 DART 3,112,621

APPARATUS FOR CONDITIONING AIR PRIOR TO PASSAGE OVER LIQUID CONDENSING MEANS Filed Oct. 17, 1960 2 Sheets-Sheet l Q INVENTOR.

Q Dav/'0 M. Dar? x Dec. 3, 1963 D. M. DART 3,112,521

APPARATUS FOR CONDITIONING AIR PRIOR TO PASSAGE OVER LIQUID CONDENSING MEANS Filed Oct. 17, 1960 2 Sheets-Sheet 2 INVENTOR. D0 v/d M. Darf TTORNEYS.

United States Patent V 3,112,621 APPARATUS FOR CGNDITEONING AIR PRHGR T0 PASSAGE OVER LiQUiD CONDENSING MEANS David M. Dart, Prairie Village, Kans., assignor to The Marley Company, Kansas City, Mo., a corporation of Delaware Filed Oct. 17, 1969, Ser. No. 63,139 11 Claims. (Cl. 62305) This invention relates to apparatus for conditioning air prior to passage of the same over liquid condensing structure, and has for its primary object, the provision of equipment for precooling air before the same is directed over refrigerant condensing means in order to increase the efiiciency of the refrigeration system and to permit sizing of the latter somewhat below the capacity which would be required if the unit was designed for operation at the maximum ambient temperature likely to be encountered during use thereof.

It is desirable, in air-cooled refrigeration systems, to provide controls for automatically maintaining the air directed over the condensing unit at a temperature as close to predetermined temperature as possible, regardless of the temperature of the ambient air. Under extremely cold conditions, it is necessary to prevent excessive cold air from passing over the condensing unit, while under high ambient air conditions, it is desirable to provide means for cooling the air prior to passage of the same over the condensing units.

It has been recognized that ambient air dry bulb temperatures are very desirable for a cooling medium whenever they are in their normal range, and for this reason, air-cooled refrigeration equipment has become widely accepted in many areas for cooling purposes. In most instances, where air is used to cool a refrigerant fluid, the size of the refrigeration equipment is determined by the maximum air temperature which is likely to be encountered in the area in which the refrigeration unit is employed. It can be seen however, that once this size is established, the equipment is too large whenever the ambient temperature is below this more or less maximum value, while in the wintertime, the capacity is several times as great as necessary. Thus, for many operational and economical reasons, it is not desirable that the unit be over-sized to compensate for an extreme temperature condition 'which might be encountered.

The problem of providing automatic control of an aircooled refrigeration unit is particularly complicated by the high temperature ambient condition which might be encountered, inasmuch as low temperature operation may be generally kept under control by utilization of dampers or the like which restrict flow of air over the condensing structure whenever the temperatures become excessively low.

Prior attempts to solve the problems referred to above have generally involved precooling the air when the ambient temperatures reach a predetermined high level, but such attempts to cool the air have not been entirely satisfactory, not only from a cost standpoint with respect to the unit itself and operation thereof, but also the difliculties encountered in providing an efiicient method of precooling the air.

It is, therefore, another significant object of the instant invention to provide apparatus for adiabatically cooling the air prior to passage of the same over a fiuid condensing unit, and in conjunction with fan means for forcing the currents of air through the precooling unit without substantial pressure drop in the currents of air forced against the condenser.

It is another significant object of the invention to provide apparatus for precooling air prior to passage of the same over condensing structure wherein the temperature of the air is lowered adiabatically by evaporating water into the latter, and with such water being directed into the air stream in the direction of movement of the latter in order to increase the velocity of such air above that attributable to fan means forming a part of the refrigeration unit.

A still further important object of the invention is to provide apparatus as referred to above, wherein the air passing through the precoo-ler and refrigeration unit housing, is caused to flow along a substantially U-shaped path of travel to thereby maintain the air in contact with the water for a maximum time to assure most efiicient cooling of the air as the water evaporates thereinto, and yet providing for maximum elimination of droplets of water entrained in such air by virtue of the fact that the air is turned through approximately 180 degrees prior to impingement of the same against the condensing unit.

Also an important object of the invention is to provide refrigeration apparatus having an air precooler wherein the means for directing water into the currents of air passing through the refrigeration unit, is adapted to propel the water through the air stream at a substantially higher velocity than the velocity of the air, to thereby increase the rate of travel of such air and reduce the pressure drop in the same as such air makes a 180 degree turn, as indicated above. In this respect, it is an object of the invention to force the water into the air and in the direction of travel thereof, at a velocity sufiicient to increase the velocity of the air to a point where the pressure drop caused by turn'mg of the air through a 180 degree are, is substantially zero.

A further important object of the invention is to provide a precooler as outlined above, which may be mounted on existing air-cooled refrigeration units with only slight modification of the latter being required, and which is particularly designed for utilization with automatic control means for limiting passage of air over the condensing unit of the refrigeration apparatus under extremely cold conditions, whereby automatic control of the temperature of the air passing through the refrigeration unit may be effectively regulated, regardless of the ambient air conditions.

A still further important object of the invention is to provide apparatus for conditioning air prior to passage of the same over liquid condensing means wherein water is introduced into such air in order to adiabatically cool the latter, but substantially all water droplets are removed from the air prior to impingement of the latter against the condenser unit to thereby preclude formation of scale and other materials on the condenser banks which would otherwise tend to limit the efiiciency of the condenser and necessitate closing down of the equipment for cleaning purposes.

In the drawings:

FIGURE 1 is a side elevational view of apparatus for conditioning air prior to passage of the same over fluidcondensing means with one side wall of the apparatus being broken away and the components therebehind being in section to more clearly indicate the construction of the instant unit;

FIG. 2 is a vertical, cross-sectional view taken substantially on line 2-2. of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a fragmentary, plan view of the apparatus and illustrating one air precooling section; and

FIG. 4 is a reduced side elevational view similar to FIG. 1.

Apparatus for conditioning air prior to passage of the same over fluid-condensing means, is broadly designated by the numeral in the drawings and includes a centr-ally disposed, fluid-condensing unit 12 having a pair is of air precooling sections 14 and 16 on opposed sides thereof.

The air-cooled condensing unit 1 2 includes a tubular housing 18 which is generally rectangular in horizontal section and is open at the upper and lower ends thereof. The lower margin of housing 33 is supported by four leg assemblies 2t? at respective corners of housing 18, and thereby maintaining the lower part of housing 18 in vertically spaced relationship to a supporting surface such as a roof or the like.

A spider frame 22 provided within housing 18 adjacent the lower margin thereof, mounts a fan assembly broadly designated 24, and including a motor 26 operably coupled to a vertical shaft 28 through belt and pulley means 30, so that during operation of motor 26, the fan 32, mounted on the lower extremity of shaft 28, is rotated about a vertical axis. It isto be noted that shaft 28 is carried by suitable bearing means 34 mounted on spider frame 22 with fan 32 being rotatable in a fan ring 36 secured to housing 18 within the lower opening therein and in concentric relationship to shaft 28.

A pair of condensing banks 38 and 40, mounted within housing 18, are disposed in dispositions presenting an inverted V, as indicated in FIG. 1, with the conduits 42 passing through respective banks 38 and 40 being connected to refrigerant headers 44 and 46 mounted on the outer wall 18a of housing 18 (see FIG. 4). The header 4 conveys fiuid to be condensed to banks 38 and 4%), while header 46 removes liquid refrigerant from conduits 42 and returns the same to the refrigeration equipment operably coupled with apparatus 16. A horizontal screen 47 is secured to the upper margin of housing 18 in spanning relationship to the opening defined thereby, to prevent leaves, sticks and other foreign materials from falling into the interior of housing 18, particularly during periods when motor 26 is not in operation.

Each of the sections :14- and 16 include a pair of opposed, upright end walls 48 disposed to engage the supporting surface for apparatus 1% with open top basins 54 being mounted on opposed end walls 48 in spanning relationship thereto. As best shown in FIG. 1, each of the basins 54 includes a horizontally disposed, transversely irregular bottom wall 52 connected to respective end walls 50 secured to end walls 48 as well as to side walls 55a and 55b extending the full length of each of the sections 14 and 16. An overflow conduit 56 passing through opposed side walls 55b and communicating with the interiors of corresponding basins 54, prevents water from overflowing from basins 54 over the upper margins thereof.

The precooler housing 58 of each of the sections 14, includes an inner vertical wall 60 provided with a generally trapezoidal, configured opening 6 2 at the lower end thereof, while the outer wall 64 of each section -14 is disposed at an angle with respect to the vertical, and is connected to the upper margin of each of the wall sections 55a in a manner so that the upper extremities 66 of each wall 64, project outwardly from a vertical plane through corresponding wall sections 5512, as best shown in FIG. 1.

The side walls 68 and 70 of each of the sections 14 and 16, are generally Z-shaped in configuration and extend upwardly from corresponding side walls 55 to the upper extremity 66 of end walls 64, as well as extremity 72 of inner walls 60. Screens 74 overlying extremities 66 and 72 of walls 64 and 60, prevent entrance of foreign materials into the vertical chambers 76 presented by walls 60, 64-, 68 and 79 of sections 14 and 16.

Each of the sections .14 and 16 is provided with a pump 78 carried by bracket means 84 secured to the outer surface of the end walls '48 at respective ends of sections 14 and 16, with water supply conduits 82 being connected to pumps 78 in communication therewith and extending upwardly to horizontal supply lines 84 carried by angle irons 36 secured within respective chambers 76 adjacent the upper extremities thereof, and connected to the inner surfaces of opposed walls 60 and 64.

A number of outwardly projecting pipes 83, secured to and communicating with corresponding lines 84, have spray nozzles 96 on the outer extremities thereof, positioned to direct sprays of water 92downwandly in chambers 76 toward basins 54. In the preferred embodiment, pipes 38 project outwardly in opposite directions from line 84 and alternate as indicated in FIG. 3.

Although separate water supply lines may "be connected to each of the pumps 78, in the construction illustrated in the drawings, the inlets (not shown) of pumps 78 communicate with respective basins 54. It is, therefore, to be preferred that a water supply line extend into each of the basins 54 in order to supply water which is lost during the evaporation process to be described in detail hereinafter. Inasmuch as it is contemplated that sections 14- and 16 be placed in operation for only a portion of the year, drains 94 are provided in one of the end walls 53 of each of the sections .14 and 16 and communicating with the interior of basins 54 to permit complete removal of water therefrom.

A pair of drain pans 96 are connected to the upper margins of opposed walls 55b of sections 14 and 16, with pans 96 being inclined toward corresponding basins 54 as shown in FIG. 1, to cause water gravitating thereon to run back into each of the basins 54.

Eliminator screens 98- extending from the outer margins 16% of each of the pans 96 to the lower edges 102 of walls 66, are generally trapezoidal in configuration as indicated in FIG. 2, and thereby close the opening 62. Screens 98 should be inclined at an angle of substantially 45 degrees with respect to the horizontal so that the same underlie the opening r164 presented by fan ring 36. 'A rectangular, flat sheet 106, having outer, upturned flanges 168, extends between opposed margins of pans 96, thereby assuring return of water to basins 54. It should be pointed out that the space between the lower margin of housing 18 and leg assemblies 20' not covered by sections 14 and '16, is open to permit inflow of air in bypassing relationship to chambers 76. In this manner, a certain part of the air permitted to enter housing 18, does not pass through cooling chambers 76. It is to be understood however, that the openings defined above in underlying relationship to housing 18, may be closed if it is deemed advantageous to have all of the air pass through precooling chambers 76.

Float controlled valve means is provided within each of the basins 54 for maintaining the level thereof at a preselected point. It is to be understood that the valve means 116 is interposed in the water supply conduit connected to each of the basins 54.

In operation, and assuming that the ambient temperature surrounding apparatus 10 is sufiiciently high to warrant precooling of the air forced through condenser banks 38 and 40, the motors of pumps 78 are energized to thereby cause water to be pumped from corresponding basins 54, upwardly through conduits 82 for distribution to respective supply lines 84. The water then is forced outwardly through horizontal pipes 88 for subsequent direction downwardly by spray nozzles 99.

Motor 26 is also actuated to cause fan 32 to be rotated within fan cylinder 36, thereby causing air to be pulled into the lower end of housing 18, through the openings between screens 98 and the lower end of housing 18, and also through the inlets presented by the upper extremities of sections 14 and'16, whereby the air moves downwardly through corresponding chambers 76, is turned degrees below edges 102, by basin 54 and pans 96, then forced upwardly through screens 98 into the interior of housing 18 via fan ring 36, next forced through condenser banks 38 and 40, and ultimately discharged through the uppermost end of housing 18 and thereby through screen 47.

Pumps 78 are of suflicient size, and operate with suflicient power to force the water emerging from sprays 92 downwardly at a velocity substantially greater than the velocity of the air passing through chambers 76 and attributable to fan means 24. The high velocity water streams serve not only to cool the air through an adiabatic process as a certain proportion of the water evaporates into the air, but also increase the velocity of suchair to thereby minimize the pressure drop in the air caused by turning of the same through approximately 180 degrees. Thus, the pressure drop, which would normally occur in the air passing through chamber 76 and thence into housing 18, is calculated without water being directed thereinto, and then the water is forced into such air in spray form as indicated in FIG. 1, with the pressure of the water being increased until the pressure drop of air entering housing 18 through fan cylinder 36, is substantially zero. a

The particles of water presenting sprays 92 moving downwardly, act against the air to thereby increase the velocity of the latter which results in minimization of the pressure drop of such air as the same impinges upon the water in basin 54, as well as pans 96, and is thereby turned upwardly toward the entrance to housing 18. Screens 98 act as eliminators for removing droplets of water entrained in the air stream flowing therethrough, and the water gravitates along the wires presenting respective screens 98 for subsequent gravitation into basins 54, through the medium of pans 96.

It is also to be recognized that turning of the air through a substantially 180 degree angle results in a large proportion of the water droplets being removed from the air stream as such droplets gravitate directly into basin 54 while the air is turned upwardly as indicated above.

The initial downward direction of air in chamber 76 and in parallel relationship to the flow of air therethrough, results in extremely eificient cooling of the air as the water evaporates into the latter, by virute of the fact that the water and air are in contacting relationship for an extended period of time and until the air can turn upwardly under the lower edge 102 of each of the vertical walls 64 The cool air passing into housing 13 is, therefore, in relatively dry condition and collection of mpisture on condenser banks 38 and 40, is maintained at a minimum which would tend to cause corrosion and build-up of mineral deposits on the coils and vanes of each of the banks 38 and 40.

The air passing into the housing 18, enters on four sides, although only the air entering at the sides occupied by sections 14 and 16 is subjected to the cooling action of the water sprays 92. Having two sides open between sections 14 and 16 minimizes the pressure drop and leaves such sides free for access and piping. Furthermore, entrance of air through two open sides, permits control of the air flow to limit pressure drop and permit proper flow of air to banks 38 and 48, regardless of whether pumps 78 are operating or not. This is important, because during the time when the pumps '78 are operating to direct sprays of water 92 into chambers 76, the aspirating eifect of nozzles 90 is sufiiceint to increase the air flow through chambers 76. Thus, when the sprays are not operating to direct water into chambers 76, the air flow would tend to fall OE and to maintain the entire units capacity, air flow must increase through the open sides between sections 14 and 16 to compensate for loss of air flow through units 14 and 16.

It is also contemplated that a thermostat be employed with units 14 and 16 so that pumps 78 are automatically actuated whenever the dry bulb temperature of the ambient air reaches some relatively high value. On this basis, the precoolers 14 and 16 will operate during any period the thermostat indicates they should, in order to provide most efiicient condensing of fluids in banks 33 and 40.

Tests have shown that when water is not supplied to chambers 76, and the-fan means 24 is operated: at a speed to cause air to pass through chambers 76 at a velocity of 400 cubic feet per minute, that a pressure drop of approximately 0.03 inch of water occurs by virtue of such air being turned through the defined degree angle. However, when water is forced downwardly in chambers 76 at a rate three to four times faster than the air velocity attributable to fan means 24, that the velocity of the air is increased and that the pressure drop is of the order of 0.0 to 0.01 inch of water.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a heat exchanger unit, the combination of a housing having an air inlet and an air outlet spaced from said inlet, there being means in the housing causing the air passing through the housing to follow a circuitous path; fluid-conducting heat exchanger structure in said housing adjacent said outlet and in said path of travel of air through said housing; power-operated means within the casing for pulling air in through said inlet, directing the same along a first portion of said circuitous path and turning the air into a second portion of the circuitous path thereof to bring said air into contacting relationship with said structure, and ultimately discharging the air through said outlet; and water spray means within the housing between said power-operated means and the air inlet for adiabatically cooling the air along said first portion of the path thereof and thereby prior to impingement of the air against said structure, said last-mentioned means including means for increasing the velocity of the air through said housing above the velocity thereof attributable to said power-operated means to thereby minimize the pressure drop in said air caused by passage of the same along said circuitous path through the housing.

2. In a heat exchanger unit, the combination of a housing having an upwardly opening air inlet and an up wardly opening air outlet spaced from said inlet, there being means in the housing causing the air passing through the housing to move downwardly from said inlet toward the lower part of the housing and thence upwardly toward said air outlet; fluid-conducting heat exchanger structure in said housing adjacent said outlet and in the upward path of travel of air through the housing; power-operated means within the housing for pulling air in through said inlet, directing the same downwardly and then upwardly toward said outlet and into contacting relationship to said structure, and ultimately discharging the air through said outlet; and means within the housing and disposed to direct water downwardly into said air as the same is moving downwardly from said inlet to adiabatically cool the air and increase the velocity thereof through said housing, prior to the change of direction of the air upwardly toward said structure.

3. A heat exchanger unit as set forth in claim 2, wherein said components include downwardly directed spray nozzles for introducing the water into said air in the form of a fine spray.

4. A heat exchanger unit as set forth in claim 3, wherein is provided means coupled to said spray nozzles for forcing the water into said air at a higher velocity than the velocity of the air as the same passes into the housing through said inlet.

5. A heat exchanger unit as set forth in claim 2, wherein said means for introducing water into said air includes a water supply pipe within the housing and extending across a portion of said air inlet, and a number of downwardly directed spray nozzles connected to and communicating with said pipe.

6. A heat exchanger unit as set forth in claim 2 wherein is provided a water collection sump adjacent the lower part of the housing and in direct underlying relationship to said air inlet.

7. A heat exchanger unit as set forth in claim 2, Where- 7 in said inlet is spaced vertically from said outlet and located below the latter.

8. In a heat exchanger unit, the combination of a housing having an upwardly opening air inlet and an upwardly opening air outlet spaced from said inlet, there being substantially vertical bafiie means in the housing, terminating in spaced relationship to the lowermost part of said housing and causing the air passing through the housing to follow a U-shaped path of travel and thereby move downwardly from said inlet toward the lower part of the housing and thence upwardly toward said air outlet; fluid-conducting heat exchanger structure in said housing adjacent said outlet and in the upward path of travel of air through the housing; power-operated means within the housing for pulling air in through said inlet, directing the same downwardly and then upwardly toward said outlet and into contacting relationship to said structure, and ultimately discharging the air through said outlet; and means within the housing and disposed to direct water into said air as the same is moving downwardly from said inlet to adiabatically cool the air and increase the velocity thereof through said housing, prior to the change of direction of the air upwardly toward said structure.

9. A heat exchanger unit as set forth in claim 8, wherein said power-operated means includes a horizontal fan disposed below said structure, the lowermost part of said bafiie means terminating adjacent said fan.

10. A heat exchanger unit as set forth in claim 9, wherein is provided eliminator means within the housing below said fan and in said path of travel of the air for removing droplets of water from the air prior to passage of the latter against said structure.

11. A heat exchanger unit as set forth in claim 1, wherein said air velocity increasing means includes components for moving a fluid through the air passing downwardly in said housing and in the same direction as said air.

References Cited in the file of this patent UNITED STATES PATENTS 20 2,154,226 Yoch Apr. 11, 1939 2,833,122 Kohl et a1 May 6, 1958 2,887,307 Koch May 19, 1959 

1. IN A HEAT EXCHANGER UNIT, THE COMBINATION OF A HOUSING HAVING AN AIR INLET AND AN AIR OUTLET SPACED FROM SAID INLET, THERE BEING MEANS IN THE HOUSING CAUSING THE AIR PASSING THROUGH THE HOUSING TO FOLLOW A CIRCUITOUS PATH; FLUID-CONDUCTING HEAT EXCHANGER STRUCTURE IN SAID HOUSING ADJACENT SAID OUTLET AND IN SAID PATH OF TRAVEL OF AIR THROUGH SAID HOUSING; POWER-OPERATED MEANS WITHIN THE CASING FOR PULLING AIR IN THROUGH SAID INLET, DIRECTING THE SAME ALONG A FIRST PORTION OF SAID CIRCUITOUS PATH AND TURNING THE AIR INTO A SECOND PORTION OF THE CIRCUITOUS PATH THEREOF TO BRING SAID AIR INTO CONTACTING RELATIONSHIP WITH SAID STRUCTURE, AND ULTIMATELY DISCHARGING THE AIR THROUGH SAID OUTLET; AND WATER SPRAY MEANS WITHIN THE HOUSING BETWEEN SAID POWER-OPERATED MEANS AND THE AIR INLET FOR ADIABATICALLY COOLING THE AIR ALONG SAID FIRST PORTION OF THE PATH THEREOF AND THEREBY PRIOR TO IMPINGEMENT OF THE AIR AGAINST SAID STRUCTURE, SAID LAST-MENTIONED MEANS INCLUDING MEANS FOR INCREASING THE VELOCITY OF THE AIR THROUGH SAID HOUSING ABOVE THE VELOCITY THEREOF ATTRIBUTABLE TO SAID POWER-OPERATED MEANS TO THEREBY MINIMIZE THE PRESSURE DROP IN SAID AIR CAUSED BY PASSAGE OF THE SAME ALONG SAID CIRCUITOUS PATH THROUGH THE HOUSING. 